Abstract
Abstract The significant chemical oxygen demand (COD) concentrations in the leachate landfill indicate substantial levels of organic contaminants, leading to an efficient and sustainable remediation strategy. Constructed wetland (CW) systems offer advantages such as affordability, simplicity, and environmental friendliness. This study used biochar and zeolite substrates, along with Pistia stratiotes L . as the pollutant absorber in the constructed wetland system. Four treatments were used in the fully randomized design of the experiment including control (P0), a constructed wetland without biomass (P1), a constructed wetland with 30 g of biomass (P2), and a constructed wetland with 60 g of biomass P3). The results showed that the constructed wetland system with 30 g biomass was more effective in reducing COD than the 60 g biomass system, with a removal efficiency of 97.56%. The COD concentration was successfully reduced to 28.75 mg/L from the initial concentration. This concentration is below the quality standard stipulated in the Minister of Environment and Forestry Decree No. 59 of 2019 concerning Landfill Leachate Quality Standards. Thus, constructed wetlands represent an effective solution for landfill leachate treatment.